This invention relates to expandable endotracheal tubes and more generally to devices adapted to be inserted into a body opening for carrying out therapeutic and other medical procedures.
An endotracheal tube typically is employed for insertion in a patient through his mouth for the purpose of ventilating his lungs. The tube passes through the normally restricted glottis or passageway between the vocal chords and may terminate adjacent the entrance to the bronchial tubes. To insure proper delivery to the lungs of the gases employed in the ventilation procedure, a off mounted on the far or distal end of the tube is inflated in situ to prevent back flow around the tube.
To accommodate patients having differently sized trachea, there is generally available to the medical practitioner a variety of endotracheal tubes of different diameters to permit selection of the proper size tube for the patient. In order to provide the most unobstructed passageway to the lungs it is desirable to insert the largest possible diameter tracheal tube acceptable to the patient.
Factors which limit the size of tube which can be utilized for a particular patient include the glottic passageway and the presence of the cuff on the outside of the distal end of the tube. Another factor is that the endotracheal tubes come in discrete sizes. To avoid possible damage to the vocal chords, it is quite often in the interest of the safety of the patient necessary to insert a smaller sized tube than the patient could safely tolerate because the next larger size is unacceptable.
In the case of children the vocal chord openings are much narrower than in adults so that there is a further restriction on the size of the diameter which can be employed, and in some children it is not possible or feasible to employ the cuff to prevent the backflow.
In addition, in some situations, the endotracheal tube must be inserted through the nose which limits further the diameter which can be tolerated.
In my U.S. Pat. No. 3,968,800 there is disclosed an adjustable endotracheal tube which was designed to overcome the problems and drawbacks associated with existing endotracheal tubes. The patented arrangement is complex and lacks the flexibility necessary to accommodate sufficiently well the varying shapes of trachea found in different patients. Another drawback is that the diameter of the tube is increased uniformly along its length and thus is limited to the expansion of the glottis in most cases. As a result there may be some backflow present.